Which of the Following Would Be the Least Likely to Qualify

Which of the following would be the least likely to qualify for a strict scrutiny or even a heightened scrutiny test by the Supreme Court to determine whether the policy is an unconstitutional violation of the equal protection clause?

A) preventing whites from attending schools designed to serve African American students
B) voter redistricting plans based on the ethnic makeup of various neighborhoods
C) a national hotel chain's policy of requiring proof of citizenship when registering
D) having different minimum ages for men and women to marry